The present application is directed to sensing technology, and more particularly, but not exclusively, to a thermocouple array for determining thermal distribution over an integrated circuit device.
Many state-of-the-art, high-performance microprocessors contain thermal sensors in order to prevent the systems from entering severe thermal conditions. Currently, off-the-shelf microprocessor designs typically adopt a diode-based and/or digital CMOS (utilizing ring oscillators and counters) sensor arrangements.
Diode-based sensor designs can have several disadvantages. Firstly, their accuracy can be affected considerably by the serial resistance of the wire connecting the remote diode and the circuit reading and processing the forward voltage of the diode. Secondly, the diodes usually exhibit a normegligible amount of nonlinearity over the normal chip operating temperature range (25° C.˜100° C.). In order to meet the target accuracy, compensation circuitry with large overhead might be needed.
Thirdly, since the diodes are susceptible to process variation, each diode needs to be calibrated individually. Digital sensors, though able to achieve a higher level of accuracy, are usually associated with larger area overhead.
Baglio et al., On-Chip Temperature Monitoring via CMOS Thermocouples in THERMINIC (2003) proposed an integrated CMOS thermocouple-based temperature sensor structure which uses junctions between metal/p+ diffused silicon or metal/polysilicon couples, also compatible with CMOS technology. Unfortunately, doping nonuniformities can cause the Seebeck coefficient of the p+ diffusion/polysilicon strip to vary along the length of the strip, hence the Seebeck voltage of these couples will depend on the temperature profile along the strip. Also, the sensor proposed by Baglio et al. uses up silicon area because the p+ diffusion/polysilicon strips have to be manufactured in the silicon layer. Moreover, placing these proposed sensors in the computationally intensive performance-critical regions typically degrades the system performance—and yet these regions usually have the highest temperature and often would benefit most from thermal monitoring—usually forcing a trade-off between system performance and sensing accuracy.
Thus, there is an ongoing need for further contributions in this area of technology. The various inventive embodiments of the present application provide such contributions.